类型:
1.普通游标 只有NEXT操作
2.滚动游标 有多种操作
1.普通游标
DECLARE @username varchar(20),@UserId varchar(100) DECLARE cursor_name CURSOR FOR --定义游标 SELECT TOP 10 UserId,UserName FROM UserInfo ORDER BY UserId DESC OPEN cursor_name --打开游标 FETCH NEXT FROM cursor_name INTO @UserId,@username --抓取下一行游标数据 WHILE @@FETCH_STATUS = 0 BEGIN PRINT '用户ID:'+@UserId+' '+'用户名:'+@username FETCH NEXT FROM cursor_name INTO @UserId,@username END CLOSE cursor_name --关闭游标 DEALLOCATE cursor_name --释放游标
结果:
用户ID:zhizhi 用户名:邓鸿芝
用户ID:yuyu 用户名:魏雨
用户ID:yujie 用户名:李玉杰
用户ID:yuanyuan 用户名:王梦缘
用户ID:YOUYOU 用户名:lisi
用户ID:yiyiren 用户名:任毅
用户ID:yanbo 用户名:王艳波
用户ID:xuxu 用户名:陈佳绪
用户ID:xiangxiang 用户名:李庆祥
用户ID:wenwen 用户名:魏文文
2.滚动游标
--带SCROLL选项的游标 SET NOCOUNT ON DECLARE C SCROLL CURSOR FOR --SCORLL 后,有了更多的游标操作(滚动游标) SELECT TOP 10 UserId,UserName FROM UserInfo ORDER BY UserId DESC OPEN C FETCH LAST FROM C --最后一行的数据,并将当前行为指定行 FETCH ABSOLUTE 4 FROM C --从第一行开始的第4行数据,并将当前行为指定行 这里的n可正可负,n>0 往下翻,n<0 往上翻 FETCH RELATIVE 3 FROM C --相对于当前行的后3行数据,并将当前行为指定行 这里的n可正可负 FETCH RELATIVE -2 FROM C --相对于当前行的前2行数据,并将当前行为指定行 FETCH PRIOR FROM C ----相对于当前行的前1行数据 FETCH FIRST FROM C --刚开始第一行的数据,并将当前行为指定行 FETCH NEXT FROM C --相对于当前行的后1行数据 CLOSE C DEALLOCATE C
结果(可以参考第一个结果分析):
具体FETCH用法:
FETCH [ [ NEXT | PRIOR | FIRST | LAST | ABSOLUTE { n | @nvar } | RELATIVE { n | @nvar } ] FROM ] { { [ GLOBAL ] cursor_name } | @cursor_variable_name } [ INTO @variable_name [ ,...n ] ]
Arguments
NEXT
Returns the result row immediately following the current row and increments the current row to the row returned. If FETCH NEXT is the first fetch against a cursor, it returns the first row in the result set. NEXT is the default cursor fetch option.
PRIOR
Returns the result row immediately preceding the current row, and decrements the current row to the row returned. If FETCH PRIOR is the first fetch against a cursor, no row is returned and the cursor is left positioned before the first row.
FIRST
Returns the first row in the cursor and makes it the current row.
LAST
Returns the last row in the cursor and makes it the current row.
ABSOLUTE { n| @nvar}
If n or @nvar is positive, returns the row n rows from the front of the cursor and makes the returned row the new current row. If n or @nvar is negative, returns the row n rows before the end of the cursor and makes the returned row the new current row. If n or @nvar is 0, no rows are returned. n must be an integer constant and @nvar must be smallint, tinyint, or int.
RELATIVE { n| @nvar}
If n or @nvar is positive, returns the row n rows beyond the current row and makes the returned row the new current row. If n or @nvar is negative, returns the row n rows prior to the current row and makes the returned row the new current row. If n or @nvar is 0, returns the current row. If FETCH RELATIVE is specified with n or @nvar set to negative numbers or 0 on the first fetch done against a cursor, no rows are returned. n must be an integer constant and @nvar must be smallint, tinyint, or int.
GLOBAL
Specifies that cursor_name refers to a global cursor.
cursor_name
Is the name of the open cursor from which the fetch should be made. If both a global and a local cursor exist with cursor_name as their name, cursor_name to the global cursor if GLOBAL is specified and to the local cursor if GLOBAL is not specified.
@cursor_variable_name
Is the name of a cursor variable referencing the open cursor from which the fetch should be made.
INTO @variable_name[ ,...n]
Allows data from the columns of a fetch to be placed into local variables. Each variable in the list, from left to right, is associated with the corresponding column in the cursor result set. The data type of each variable must either match or be a supported implicit conversion of the data type of the corresponding result set column. The number of variables must match the number of columns in the cursor select list.
以上就是详解SQL游标的用法的详细内容,更多关于SQL游标用法的资料请关注其它相关文章!
免责声明:本站资源来自互联网收集,仅供用于学习和交流,请遵循相关法律法规,本站一切资源不代表本站立场,如有侵权、后门、不妥请联系本站删除!
P70系列延期,华为新旗舰将在下月发布
3月20日消息,近期博主@数码闲聊站 透露,原定三月份发布的华为新旗舰P70系列延期发布,预计4月份上市。
而博主@定焦数码 爆料,华为的P70系列在定位上已经超过了Mate60,成为了重要的旗舰系列之一。它肩负着重返影像领域顶尖的使命。那么这次P70会带来哪些令人惊艳的创新呢?
根据目前爆料的消息来看,华为P70系列将推出三个版本,其中P70和P70 Pro采用了三角形的摄像头模组设计,而P70 Art则采用了与上一代P60 Art相似的不规则形状设计。这样的外观是否好看见仁见智,但辨识度绝对拉满。
更新日志
- 小骆驼-《草原狼2(蓝光CD)》[原抓WAV+CUE]
- 群星《欢迎来到我身边 电影原声专辑》[320K/MP3][105.02MB]
- 群星《欢迎来到我身边 电影原声专辑》[FLAC/分轨][480.9MB]
- 雷婷《梦里蓝天HQⅡ》 2023头版限量编号低速原抓[WAV+CUE][463M]
- 群星《2024好听新歌42》AI调整音效【WAV分轨】
- 王思雨-《思念陪着鸿雁飞》WAV
- 王思雨《喜马拉雅HQ》头版限量编号[WAV+CUE]
- 李健《无时无刻》[WAV+CUE][590M]
- 陈奕迅《酝酿》[WAV分轨][502M]
- 卓依婷《化蝶》2CD[WAV+CUE][1.1G]
- 群星《吉他王(黑胶CD)》[WAV+CUE]
- 齐秦《穿乐(穿越)》[WAV+CUE]
- 发烧珍品《数位CD音响测试-动向效果(九)》【WAV+CUE】
- 邝美云《邝美云精装歌集》[DSF][1.6G]
- 吕方《爱一回伤一回》[WAV+CUE][454M]